1. Field of the Invention
This invention relates in general to sugar beet pectins. In one aspect, this invention is directed to a pectin extract obtained from sugar beet. In another aspect, this invention relates to sugar beet pectin having utility in comestibles.
2. Background of the Related Art
Spent sugar beet pulp consists largely of structural polysaccharide complexes associated with the primary cell wall of parenchymatous tissue. This tissue has been subjected to an exhaustive hot water extraction to remove sugar and other intracellular constituents. Subsequent extraction of spent beet pulp under hydrolytic conditions generates solubilized forms of the non-cellulosic components whose yield and chemical classification vary depending on the severity of hydrolysis condition and the specific extractive method employed. Past reports tended to segregate the solubilized polysaccharides into largely neutral carbohydrate complexes (hemicelluloses) and acidic carbohydrate complexes (pectins). More recent investigations suggest that both the neutral and acidic carbohydrates may be covalently associated components of the non-cellulosic structural macropolysaccharides compromising the cell wall of parenchymatous plant tissue. These reports imply that hemicellulose or pectin isolates represent highly heterogeneous fragments resulting from natural or induced hydrolysis occurring during their preparation. (F. M. Rombouts and J. F. Thibault, "Sugar Beet Pectins: Chemical Structure and Gelation Through Oxidative Coupling" in Chemistry and Function of Pectins, pp. 49-60, 1986, edited by M. L. Fishman and J. J. Jen, ACS, Washington, D. C.; I.C.M. Dea and J. K. Madden, "Acetylated Pectic Polysaccharides of Sugar Beet" in Food Hydrocolloids, Vol. 1, pp. 71-88, 1986; L. Phatak, K. C. Chang and G. Brown, "Isolation and Characterization of Pectin in Sugar Beet Pulp" in J. of Food Science, Vol. 53, pp. 830-833, 1988). These and other investigators postulate a rhamnogalacturonide backbone with neutral sugar appendages composed largely of arabinogalactan emanating from the backbone in clusters along the chain. Several types of ester functionality are present -- the uronic acid component of the backbone is highly esterified as the methylester feruloyelster groups are believed to be located on the neutral carbohydrate appendages and a substantial degree of acetyl ester function is present which cannot at present be assigned to either pendant or backbone structure (or both). For descriptive purpose associated with the specification of this invention and the appended claims, the polysaccharide complex isolated by extractive hydrolysis of spent sugar beet pulp as described herein will be referred to as a pectin, or modified pectin.
Commercial pectins are derived from citrus and apple pulps. They are characterized by high viscosity of low solids aqueous solutions and form gels in the presence of high solids sucrose solutions under mildly acidic conditions. Commercial pectins derived from other plant sources have long been sought. Commercial pectin production from sugar beet commenced in Europe during World War II but ceased when citrus and apple pulps again became available. Sugar beet pectins were generally of inferior jelly grade and their function was enhanced by conversion to low ester pectinic acids which produce ionically crosslinked gels in the presence of polyvalent cations (R. H. McDowell, U.K. Patent 555,842, Sept. 9, 1943). Probably because of a preoccupation with commercial pectin replacement in jams, jellies and gels which still persists (F. M. Rombouts, J. F. Thibault and C. Merrier, French Patent 8,307,208, 1983) there has been virtuallY no other commercial use of this interesting hydrocolloid complex. While others have commented academically on potential application based on chemical or physical characterization, there has been no reduction to practice of any use of beet pectin other than that of its use as a gel forming additive in fruit spreads.
Moreover, prior to the present invention, there was no process available which utilized a plug flow reactor to achieve hydrolytic extractions which provide a sugar beet pectin having properties which extended their scope of utility beyond jams, jellies and similar fruit spreads.
Accordingly, one or more of the following objects can be achieved by the practice of the present invention. It is an object of this invention to provide a sugar beet pectin extract having utility in comestibles. Another object of this invention is to provide a sugar beet pectin extract having characteristics not possessed by commercially available pectin products. A further object of this invention is to provide sugar beet pectins having applications in comestibles other than in fruit spreads. Another object of this invention is to provide sugar beet pectins having emulsion stabilizing properties for comestibles, such as flavor oils, vegetable oils, dairy products and the like. A further object is to provide sugar beet pectins which supply a source of soluble dietary fiber which can be added to comestibles. A still further object is to provide sugar beet pectins which can replace loss of texture or mouth feel when sugar substitutes are used in the preparation of comestibles. A further object is to provide a non-hydroscopic adhesive or film former for binding granulated or extruded food products. These and other objects will be readily apparent to those skilled in the art in the light of the teachings herein set forth.